发光学报, 2017, 38 (7): 978, 网络出版: 2017-07-05  

X射线成像积分滤波模型与实验

X-ray Imaging Integral Filter Model and Experiment
作者单位
长春理工大学 理学院, 吉林 长春 130022
摘要
X射线数字化成像系统的不足主要表现在成像末端耦合约束、微焦点约束瓶颈以及单光子成像缺陷与量子噪声约束等方面, 利用传统的数字图像处理手段很难实现有效的图像滤波, 而复杂的滤波算法进一步限制了其工程使用效果。为了提高X射线成像系统的光学传递能力与系统抗噪声能力, 本文首先以热激发X辐射源与X射线像增强器为例, 从系统层面探索成像遇到的诸多技术瓶颈, 并在此基础上提出了一种针对X射线成像的积分滤波方法。然后, 将空间频率固定的铅制光栅作为被测目标, 通过改变中继光学耦合系统的物像关系使得像方空间频率在一定区间内连续改变, 进而通过大量的实验数据实现在不同积分时间条件下的光学传递函数精确拟合。接着, 分别从光学传递函数积分效果与归一化后的基频传递特性的角度验证了该滤波方法可以有效压制热触发源引入的量子噪声, 避免图像产生单光子成像缺陷。实验数据表明: 该方法可以提升系统成像的光学传递能力。最后, 通过帧叠加与积分滤波的对比效果验证了该滤波方法的优越性。
Abstract
Deficiencies of X-ray digital imaging system are mainly shown in the following aspects: imaging end coupling constrained, bottleneck constrained by microfocus, photonic defect and constrained quantum noise, etc.. It is difficult for the effective image filtering through traditional digital image processing techniques to be realized. Its effect is further constrained by the complicated filtering algorithm. To improve the optical transmission capacity and system noise immunity of X-ray imaging system, in this paper, the thermal excited X-ray source and X-ray image intensifier were taken as examples, a number of imaging technical difficulties were explored from system level, and a integral filtering method on X-ray imaging was put forward. Then, the frequency-fixed leaden raster was taken as the tested object. By changing the object-image relation of relay optical coupling system, the image place frequency could be changed continuously within a certain range. By lots of experimental data, the accurate fitness of OTF (optical transfer function) can be realized under different integral time conditions. It is proved that this filtering method can not only effectively suppress the quantum noise caused by hot trigger source in avoid of photonic defect on image, but also obviously improve the optical transmission capacity of imaging system from angles of OTF integral effect and normalized baseband transmission characteristics respectively. Finally, the superiority of this filtering method was testified from perspective of contrasting frame-adding and integral filtering.

刘春阳, 王贺, 母一宁. X射线成像积分滤波模型与实验[J]. 发光学报, 2017, 38(7): 978. LIU Chun-yang, WANG He, MU Yi-ning. X-ray Imaging Integral Filter Model and Experiment[J]. Chinese Journal of Luminescence, 2017, 38(7): 978.

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